When it comes to Halloween, no family goes harder than the Kardashians. The minute October hits, Calabasas is filled with huge pumpkins lining the driveways of their mansions and the dress-up parties begin as early as a fortnight in (this year, Kylie Jenner dressed as a green witch with Hailey Bieber came in first place).

So when Kim Kardashian found out her friend was having a party on Halloween weekend, it makes sense she’d assume it was a costume party. However, on this occasion it appears she was a little off the mark.

The SKIMS founder took to Instagram to reveal she went to Tracee Ellis Ross’ birthday dinner entirely covered in blue welts. In the image, Kardashian is dressed as X-Men’s Marvel heroine Mystique, complete with red hair and a painted face. But, as she noted on her stories, her choice of clothing may not have totally matched the theme — which appears to have been nothing more than your usual birthday glam.

“That time I showed to a birthday dinner in full costume when it wasn’t a costume party!” Kardashian wrote alongside a photo of Ross — thankfully, not looking too upset by her guest’s attire — wearing a red sequin outfit. “Happy Birthday to the most beautiful kind soul @traceeellisross.”

Kardashian’s take on the X-Men mutant involved dressing in a blue latex skintight bodysuit with prosthetic bumps, electric blue face paint and bright yellow contact lenses. She dyed her hair red for the occasion and slicked-back her hair, adding blue stilettos to finish the look.

Kardashian and Kanye West’s children also dressed up for the spooky season this year, all of whom chanelling music icons for their costumes. On Instagram, Kardashian posted a carousel showing North, 9, Saint, 6, Chicago, 4, and Psalm, 3 as Aaliyah, Snoop Dogg, Sade, and Easy E, writing, “THE ICONS,” as the caption.